1. Field of the Invention
This invention relates to restraint systems and seat systems and more particularly to a seat insert, insertable within the existing seat of a vehicle, for protecting the crew member of the vehicle from high "G" accelerations resulting from aircraft maneuvers and/or emergency ejections from the aircraft.
2. Description of the Related Art
Modern high performance fighter aircraft are capable of flight maneuvers which subject the crew members to very high accelerations, "G's", particularly in the head-to-foot direction. Severe stresses are placed upon the crew members by such aircraft maneuvers. Indeed, many modern aircraft are capable of aerial maneuvers which are beyond the tolerance of the human crew members. Consequently, fighter aircraft and their crew members are occasionally lost as a result of pilot G-induced Loss of Consciousness (G-LOC).
Aircraft equipment malfunction or adverse environmental conditions ma occasionally make proper control of the aircraft so difficult as to render it improbable that the aircraft can be safely landed. Enemy fire in combat situations may seriously disable an aircraft or crew member making it also improbable that the aircraft can be brought to a safe landing. In such situations, ejection of the crew members from the aircraft may be desirable. However, in some such situations, the high forces of acceleration generated by catapult ejection systems may be added to the forces generated by the motion of the aircraft and the total forces may thus exceed the tolerance of the crew members. Consequently, pilots and their crew members are occasionally killed or severely disabled as a result of ejection from an aircraft.
Several approaches have been proposed for solving the problem of high "G" accelerations. For example, U.S. Pat. No. 4,664,341 issued to R. J. Cummings, entitled "Head Restraint System" (assigned to Rockwell International Corporation), discloses a system which helps enable free and unencumbered head movement during tolerable lateral inertia forces, while locking in place and protecting the pilot's head during periods of high lateral inertia forces. The invention utilizes a helmet that rotates on a track and in an inertia reel, which will lock when lateral forces exceed predetermined levels.
Co-pending U.S. Ser. No. 175,660, by S. G. Wurst, entitled "High G Protection System" (assigned to Rockwell International Corporation), discloses a seat restraint system for supporting the occupant in a leaned forward or crouched position. This results in a reduced hydrostatic blood column (the distance between the aorta and retina of the eye). The Wurst Application discloses a rigid support plate for supporting the occupant's upper torso when in a forwardly crouched postion. The support plate is pivotly connected to the seat by a U-joint. A spring is utilized to maintain a force with a magnitude proportional to the G-induced forces. A seat pan is disclosed which is upwardly rotatable to augment the angle of crouch of the occupant while his forearms are rested on appropriately positioned arm rests to also provide support to the upper torso.
U.S. Pat. Ser. No. 865,508 to E. A. Smith, B. J. Courter, and S. G. Wurst, entitled "Forward Posture Support Seat System" (also assigned to Rockwell International Corporation) discloses a restraint system which helps provide protection against the compression of the vertebrae of the spine caused by high G-induced forces resulting from ejection from the aircraft as well as aircraft maneuvers. The invention utilizes a seat insert which is rotatably connected to the seat to provide multi-axis rotation (allows crew member to turn in the seat). Such a rotation is provided by a ball-type joint and telescoping strut. The Smith patent also teaches use of a strap harness which secures the crew member to the seat back; an inertia reel; and torso support means, which is lockable when the crew member is in a crouched over position such that fore and aft motion of the crew member is substantially precluded. Although providing some protection against compression of the vertebrae of the spine caused by high forces of acceleration, the Smith patent does not address the issue of reducing the risk of injury to the spine during seating postures ranging from upright to full forward lean (approximately 42.degree.).
Other prior art systems for providing the crew member protection against G-induced forces include strap restraints and cord systems for retaining the pilot or crew members firmly against the seat. Such systems may use a pair of cords connecting the sides of the helmet to the shoulders of the pilot or crew member. Another pair of cords are attached to the first pair and secured to a reeling in device at the back of the seat in order to pull the pilot's helmet and shoulders firmly against the seat upon the application of forces of acceleration. Such restraint systems may be unduly complex and severely limit the movement of the crew member in the seat. An example of such a restraint system is U.S. Pat. No. 3,329,464 issued to A. J. Barwood.
Some prior art systems use a pad positioned over the chest of the crew member to apply restraint directly to the crew member's chest. However, such chest pads are functionally the same as and, thus, no more effective than the strap restraint system described herein above. Two examples of such prior art restraint systems using chest pads are U.S. Pat. 3,852,679 issued to H. Y. de Lavenne and U.S. Pat. No. 4,300,799 issued to D. J. Cunningham.
Although restraint of the head and upper torso prevents excessive forward bending of the body, restraint results in compressive forces along the spine. These forces generate back and neck pain. A seat system is thus needed that will provide protection against the compression of the vertebrae of the spine caused by high forces of acceleration resulting from ejection from the aircraft, as well as aircraft maneuvers, while still allowing sufficient pilot mobility, good visibility, and good access to the controls.